Pg 102: Building, hewing or drilling any amount or permanence is Biblically prohibited on the Sabbath.
Pg 103: Plowing, weeding or pruning any amount is Biblically prohibited on the Sabbath.
Pg 104: God does not prevent one who seeks to defile himself, but does assist one who seeks to purify himself.
Chapter 12 Summary: “Haboneh”: The act of construction includes any action that builds or improves a structure or part of it. Plowing includes any action that improves the condition of the soil. There is no “minimum” quantity for the above two that creates liability (i.e. one is liable for even the most minute act of construction or plowing). The “minimum” biblical liability for writing is two characters written conventionally.